1. FIELD OF THE INVENTION
The present invention is directed to a novel brominating and oxidizing agent and its method of application. More specifically, the present invention is directed to certain 3-bromo-2-oxazolidinones characterized as being highly stable and less polar with respect to the N-Br bond contained within the molecular structure thereof.
2. DESCRIPTION OF THE PRIOR ART
Walles U.S. Pat. No. 3,591,601 (patented July 6, 1971) discloses certain 3-halo-2-oxazolidinones having the formula: ##STR2## where X is broadly defined as bromine or chlorine, and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are broadly defined, inter alia, as hydrogen or lower-alkyl containing from one to four carbon atoms. The compounds are said to be useful "in germicidal, bleaching, and chemical reaction applications."
While the above definitions are broadly embracive of compounds having a quaternary carbon at the 4- and/or 5-positions of the oxazolidinone ring, i.e., compounds where either each of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is lower-alkyl or compounds where each of R.sub.1 and R.sub.2 or each of R.sub.3 and R.sub.4 is lower-alkyl (the other pair being hydrogen), such compounds are not specifically taught by Walles, who discloses only compounds where the 4- and 5-carbon atoms are either unsubstituted or where either one or both of the 4- and 5-carbon atoms bear a single lower-alkyl group. Thus, of the 2-oxazolidinones having the above general structure where each of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are either hydrogen or lower-alkyl, Walles discloses only the following species. (The "Walles Cpd. Nos." are adopted here for reference purposes hereinafter.)
______________________________________ Walles Cpd. No. R.sub.1 R.sub.2 R.sub.3 R.sub.4 X ______________________________________ 1 CH.sub.3 H H H Cl 2 C.sub.2 H.sub.5 H H H Cl 3 H H H H Cl 4 CH.sub.3 H H H Br 5 CH.sub.3 H CH.sub.3 H Cl 6 C.sub.4 H.sub.9 H H H Br ______________________________________
Certain of the above-listed Walles compounds have been prepared and it has been found that they are unstable and consequently have limited usefulness as germicidal agents. On the other hand, it has been surprisingly found that certain compounds within the ambit of the very broad disclosure of the patentee, but not specifically contemplated thereby, are suprisingly stable, in contrast with the compounds actually prepared by Walles, and possess unexpected advantageous properties as brominating and oxidizing agents.
A number of brominating agents are known to date, e.g., N-bromoacetamide, N-bromophthalimide, and N-bromosuccinimide (NBS), the latter of which is the most popular. Though, N-bromosuccinimide is usually the brominating agent of choice, this compound is quite disadvantageous from the following standpoint:
1. Firstly, it is unstable at ambient temperatures, and as such, it must be stored at temperatures ranging from 0.degree. C or below, in order to avoid the relatively fast release of Br.sub.2.
2. Secondly, although this compound has a relatively nonpolar N-Br bond, the polarity of the N-Br bond is sufficient to lead to an easy release of "positive" bromine (Br.sup.+), a feature unwanted for certain bromination procedures. That is, it is more desirable in these specific bromination procedures that only "radical" bromine (Br.) be released.
3. Thirdly, from an economic standpoint, N-bromosuccinimide is quite costly to produce.
Extensive studies have shown that the polarity of the N-Br bond contained in the molecular structure of N-bromoamides and bromoimides parallels the strength of the acid from which the particular bromoamide or bromoimide is derived. Thus, it was speculated that since succinic acid is one of the weaker acids known, its corresponding bromoimide (N-bromosuccinimide) would have a relatively non-polar N-Br bond.
The present inventors have recognized that carbonic acid is a significantly weaker acid than succinic acid, and thus, its N-bromoamide or bromoimide possesses an N-Br bond of lower polarity leading to a more stable and more selective brominating and oxidizing agent.
Since it has heen shown that the 5-membered ring of N-bromosuccinimide creates favorable structural conditions for most brominating reactions, the present inventor has intended to maintain the 5-membered ring structure for a useful-N-bromo compound derived from carbonic acid, i.e., the compounds of the instant invention.
From the foregoing, it is apparent that a need exists for a brominating and oxidizing agent which is substantially more stable than N-bromosuccinimide, less polar than N-bromosuccinimide with respect to the N-Br bond, and less costly from a preparatory standpoint.